Hydrodessus brevis, Miller, Kelly B., 2016

Miller, Kelly B., 2016, Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini), ZooKeys 580, pp. 45-124 : 67

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus brevis sp. n. Figs 12, 44

Type locality.

Venezuela, Amazonas, Cerro de la Neblina, basecamp, 0.833°N, 66.167°W.

Diagnosis.

This species has the lateral elytral carina relatively short, present just at the humeral angle, and the body overall approximately concolorous dark red (Fig. 12A). Hydrodessus brevis is similar to Hydrodessus palus in shape, and other structures, but that species is pale yellow, a bit smaller (TL = 2.0 mm) with Hydrodessus brevis larger (TL = 2.5 mm). The male genitalia differ, as well, with the median lobe of Hydrodessus brevis broader and apically not sinuate. Hydrodessus brevis is extremely similar to Hydrodessus pereirai , but that species is considerably larger (TL = 3.9 mm). The male genitalia of Hydrodessus pereirai are unknown so were not compared.

Description.

Measurements. TL = 2.6 mm, GW = 1.2 mm, PW = 1.0 mm, HW = 0.7 mm, EW = 0.5 mm, TL/GW = 2.2, HW/EW = 1.5. Body shape elongate, apically pointed, lateral margin distinctly discontinous between pronotum and elytron (Fig. 12A).

Coloration (Fig. 12A). Head and pronotum red. Elytra red, distinctly darker than head and pronotum, lighter apically, elytra immaculate (Fig. 12A). Antennae, palps and legs yellow to red-yellow. Venter red, lighter laterally on prothorax, elytral epipleuron and apex of abdomen.

Sculpture and structure. Head broad, anterior clypeal margin broadly rounded; surface shiny with fine, indistinct punctures; eyes small. Pronotum slightly cordate, broadest slightly anterior of middle (Fig. 12A); lateral bead fine; surface shiny and covered with very fine punctures. Elytra elongate, apically pointed, lateral margins slightly and broadly curved (Fig. 12A); lateral carina distinct but short, about 1/5 length of elytra (Fig. 12B); surface covered with fine punctures. Prosternum medially carinate and setose; prosternal process very broad, broadest at anterior lateral lobes, lateral carinae evenly convergent to broadly truncate apex, deeply excavated medially (Fig. 12C). Metaventrite with anterior process moderately broad, apically truncate, medially somewhat excavated; metasternal carinae distinct, curved medially and diverging posteriorly, terminating near anterior ends of metacoxal lines (Fig. 12C); surfaces covered with fine punctures. Legs with most surfaces covered with fine punctation throughout; pro- and mesotibiae slender; metatibia with posteroapical brush of setae distinctive; metatrochanter distinctly offset, apically rounded; metacoxa covered with fine punctures; metacoxal lines subparallel, moderately closely approximated, slightly convergent anteriorly (Fig. 12C). Abdomen covered with fine punctation; ventrite VI apically narrowly rounded.

Male genitalia. Median lobe bilaterally symmetrical, in lateral aspect broadly curved, curvature more pronounced basally, basal region broad, rounded, apical portion slender, slightly expanded submedially along ventral margin, apex slender and narrowly rounded (Fig. 12D); in ventral aspect basally narrow, lateral margins evenly curved and apically evenly convergent to angulate apex (Fig. 12E). Lateral lobe slender, moderately broad basally, elongate triangular apically with lateral margins evenly convergent to rounded apex (Fig. 12F).

Female genitalia. Not examined.

Sexual dimorphism. Male pro- and mesotarsi I–III slightly more broadly expanded than female and ventrally with several large adhesive setae.

Variation. No significant variation was observed in the few specimens examined.

Etymology.

This species is named brevis, Latin for “short,” for the relatively short lateral elytral carina in specimens.

Distribution.

Hydrodessus brevis is known only from Cerro de la Neblina, Amazonas, Venezuela (Fig. 44).

Habitat.

The two specimens in the type series were collected from leaf pack from among rocks in a small rainforest stream.

Specimens.

The holotype male is in MIZA labeled, "VENEZUELA,T.F.Amaz. Cerro de la Neblina Basecamp. 140 m. 0°50'N, 66°10'W 18 February 1985/ From leaf pack among rocks in small stream in rainforest P.J. & P.M.Spangler, R.Faitoute, W.Steiner/ HOLOTYPE Hydrodessus brevis Miller, 2016 [red line with black line border]."

Paratypes, 4 total. Venezuela, Amazonas, Cerro de la Neblina, basecamp, 0.833°N, 66.167°W, 7 Feb 1985, leaf pack among rocks in small stream in rainforest P.J. Spangler, P.M. Spangler, R. Faitoute, W. Steiner (4, MIZA, USNM).